1. Field of the Invention
The present invention relates to a fuel filter with at least one filter element and connections for the fuel supply and fuel outlet.
2. Description of the Prior Art
A fuel filter of the type with which this invention is concerned, known from DE 198 11 689 A1 has a housing made of solid plastic and has a beaker-shaped bottom part and a lid-like top part that is detachably fastened to the beaker-shaped bottom part by means of a quick release. The beaker-shaped bottom housing part contains a hollow, cylindrical star filter that rests on a pedestal section. The pedestal section contains a sump for water separated out during filtration of the fuel and a water drain that can be closed by means of a screw plug. In addition, the pedestal region is provided with a fuel inlet that feeds into an inlet duct for a heating unit welded in place beneath the pedestal section. The pedestal section is also provided with an outlet duct that allows the fuel to travel from the heating unit to the dirty side of the filter. The flow passes through the filter insert radially from the outside to the inside. Its clean side is connected to an outlet fitting via which the cleaned fuel can be drained off in the direction of the engine via a first duct. In addition, the outlet fitting is provided with a second duct, which can be closed by an overflow valve and permits the fuel to be returned to the tank. The clean side of the filter is also connected to the sump.
Fuel filters of this kind are used, among other things, in the engines of motor vehicles.
One problem of these previously known filters is that they are comparatively bulky and are difficult to integrate into the engine compartment of a vehicle.
In this respect, the object of the present invention is to develop a fuel filter that permits a compact design. This object is attained with a fuel filter of the type mentioned at the beginning in that the filter element is embodied as flat.
A surprising discovery has been made that instead of star filter inserts, it is possible to use flat filter elements in which the clean side and the dirty side are situated essentially parallel to each other. This makes it possible to embody the fuel filter as a whole as flat and for it therefore to be significantly flatter than would be possible with the use of star filter inserts, while providing the same through flow capacity. This yields a significantly greater possibly structural variety, thus allowing the form of the fuel filter to be better adapted to the space available in the engine compartment.
The folding of the filter material advantageously produces a block-like or box-shaped filter element with a good stability and a large surface area.
In a preferred embodiment form of the present invention, the clean side of the filter element is encapsulated and connected to the fuel outlet. An encapsulation of this kind can, for example, be comprised of caps for covering the top side and the upper and lower ends of the filter element, and a side wall encompassing the clean side of the filter element, each made of plastic. A filter element embodied in this way can easily be inserted into a fuel filter housing without requiring an additional seal between the clean side of the filter element and its dirty side. Additional structural features and components inside the housing for dividing the clean side from the dirty side are thus rendered superfluous; the dirty side of the filter can encompass the encapsulated filter element as completely as possible.
In addition or conversely, the dirty side of the filter element can be correspondingly encapsulated and connected to the fuel inlet.
In another embodiment of the fuel filter according to the present invention, two or more filter elements are provided, which can be situated for example adjacent to each other at their upper, lower, or lateral sides, and essentially in a single plane, but can also be situated in planes extending at an angle to each other.
In an additional preferred embodiment of the present invention, the fuel inlet and the fuel outlet are situated at one end of the fuel filter or at opposite ends of the fuel filter. This makes it possible to assure that the advantage of a flat design is not canceled out by connections protruding beyond the fuel filter.
In another preferred embodiment, the flow entry of the fuel into the fuel filter housing is designed to reduce or eliminate turbulence in the region of the bottom of the fuel filter, particularly when it is horizontally oriented. It has turned out to be particularly effective to use a flow baffle in the region of the fuel inlet, which is preferably inclined upward and thus deflects the flow toward the top of the fuel filter housing.
The inlet distribution stabilizer advantageously provides for particularly favorable filtration properties of the fuel filter while requiring a remarkably low overall volume of the fuel filter.